Self-propelled elevator systems, also referred to as ropeless elevator systems, are useful in certain applications (e.g., high rise buildings) where the mass of the ropes for a roped system is prohibitive and there is a desire for multiple elevator cars to travel in a single lane. There exist self-propelled elevator systems in which a first lane is designated for upward traveling elevator cars and a second lane is designated for downward traveling elevator cars. Existing self-propelled elevator systems may operate more than one elevator car in a lane, and have elevator cars traveling in different directions in a single lane. At least one transfer station is provided in the hoistway to move cars horizontally between a first lane and a second lane. As elevator cars enter and exit a horizontal transfer station, it is important that the elevator cars are controlled so as to not interfere with each other.